Several types of drill bits can be used to drill a wellbore for hydrocarbon extraction or for any other purpose. One type of drill bit is a roller cone bit, alternately referred to as a rotary cone bit or a rock bit. Briefly, roller cone bits commonly include a plurality of cutter cone assemblies (typically three) rotatably coupled to a bit body. As the bit body is rotated about its central axis, the cutter cone assemblies cooperatively grind and crush underlying rock to form a wellbore.
Roller cone bits also typically include an internal lubrication system that uses a fairly viscous lubricant. The lubricant is retained within the lubrication system using one or more sealing elements strategically positioned in each cutter cone assembly. The sealing elements prevent the migration of fluids and/or debris into the interior portions of the cutter cone assemblies, which could otherwise contaminate vital bearing surfaces and thereby reduce the operational lifespan of the roller cone bit.
Such sealing elements can wear rather rapidly because of the harsh and abrasive environments in which roller cone bits commonly operate. For instance, during operation the sealing elements are commonly subjected to drilling fluids, which can contain fine abrasive particulates, such as bentonite and drill cuttings. The sealing elements are also commonly subjected to high temperatures, large pressure fluctuations, and dynamic movement between the cutter cone assemblies and the bit body. A good sealing element design must have the ability to continue to perform its sealing function under these harsh and abrasive environments with a low leakage rate, and the design must also preferably offer an extended service life.